Eosinophils are a type of white blood cell found in horses that are involved in the immune response, particularly in allergic reactions and parasitic infections. They are part of the body's defense system and can be found in various tissues, including the blood, lungs, and gastrointestinal tract. Eosinophils contain granules filled with enzymes and proteins that can be released to combat pathogens. Their presence and concentration can vary in response to different physiological conditions and diseases. This page compiles peer-reviewed research studies and scholarly articles that explore the function, regulation, and clinical implications of eosinophils in equine health, including their role in disease processes and potential as diagnostic markers.
Becht JL, Semrad SD.Hematologic parameters change during the first 10 days of life. Erythrocytes increase in number but decrease in size and hemoglobin concentration. The PCV, hemoglobin, and platelet count also decrease. Total blood and plasma volume and, to lesser extent, erythrocyte volume decrease. Normal neonatal foals may have immature neutrophils (up to 5 per cent bands), and their early rapid rise in neutrophil numbers may be accompanied by a lymphopenia. Monocytes, eosinophils, and basophils are all absent or low initially. Infectious processes can cause rapid and variable changes in the leukogram. Howev...
Gill J, Kompanowska-Jezierska E, Jakubow K, Kott A, Szumska D.In 34 pure-breed Arabian horses divided into four groups (Gr. I, ten pregnant mares; Gr. II, seven barren mares; Gr. III, ten foals born in 1981; Gr. IV, seven foals born in 1982) seasonal changes in the white blood cell system, cortisol level and lyzozyme activity were studied. Seasonal periodicity was found in all groups for the number of lymphocytes, segmented neutrophils and eosinophils and cortisol level. Leukocyte periodicity was found in three groups, but not in the barren mares. In lyzozyme activity there was periodicity in three groups but not in the youngest foals. In the stab neutro...
Bailey M, Kent J, Martin SC, Lloyd S, Soulsby EJ.The concentrations of serum proteins (beta 1, beta 2, gamma, alpha 1, alpha 2 globulins and albumin) and absolute numbers of eosinophils, neutrophils and lymphocytes were examined in 64 naturally infected horses and ponies in which the number of larvae of Strongylus vulgaris in the cranial mesenteric artery and the severity of the lesion of verminous arteritis could be determined. The horses were grouped according to the number of larvae found and the severity of the arteritis. The results demonstrated that, although some significant deviation from a random distribution occurred in certain of ...
Floyd K, Suter PF, Lutz H.Direct staining of the granules of blood eosinophils by anti-immunoglobulin fluorescein isothiocyanate (FITC) conjugates was observed when feline blood smears were tested for presence of feline leukemia virus (FeLV) antigen by immunofluorescent antibody. When blood smears of other species including swine, horses, cattle, dogs, sheep, birds, and human beings were examined, direct staining of eosinophils by FITC conjugates was also detected. This FITC staining was restricted to eosinophils and was not observed in neutrophils, lymphocytes, and platelets. Direct FITC staining of eosinophils does n...
Jörg A, Henderson WR, Murphy RC, Klebanoff SJ.Horse eosinophils purified to greater than 98% generated slow reacting substance (SRS) when incubated with the calcium ionophore A23187. On a per cell basis, eosinophils generated four to five times the SRS produced by similarly treated horse neutrophils. Eosinophil SRS production was inhibited by 5,8,11,14-eicosatetraynoic acid and augmented by indomethacin and arachidonic acid, suggesting that it was a product(s) of the lipoxygenase pathway of arachidonic acid metabolism. Compounds with SRS activity were purified by high-pressure liquid chromatography (HPLC) and identified by ultraviolet spe...
Maxwell MH.A series of experiments is described in which attempts were made to produce an avian eosinophilia using various agents. Although none of the experiments was decisive, two demonstrated a slight rise in the eosinophil counts. In one experiment horse serum was injected into a group of fowls on alternate days for 42 days. No eosinophils were seen in any blood smears after this treatment. After a rest period of eight days the birds received further injections for 10 days. The mean eosinophil count rose to over 4 per cent with a range of 1 to 11 per cent. It is considered that this type of response ...
Dixon JB, Allan D, West CR.The purpose of these investigations was to assemble and compare data which might illustrate a functional relationship between phytohaemagglutinin-induced transformation of equine lymphocytes in vitro and the haematological profiles of the lymphocyte donors. Statistically significant correlation between transformation and a haematological parameter was taken as evidence that both may be part of a common regulatory system. There was no evidence that transformation in vitro was affected by artefactual variation in the cellular composition of the cultures. Transformational behaviour of lymphocytes...
Baker KP, Quinn PJ.Sweet itch is an intensely pruritic dermatitis of horses recurring annually in Ireland from April to November. The tissue changes of sweet itch have similarities to immediate-type hypersensitivity reactions which occur in skin sensitised to the saliva of bloodsucking insects. There was subepidermal oedema, and marked eosinophilia; the blood vessels were tortuous and enlarged. Microfilaria were not found in serial sections of lesions of 5 affected horses. The histopathology of the immediate dermal remal reaction to the intradermal injection of Culicoides extract shows dermal vasodilation and eo...
Hodgin EC, McGuire TC, Perryman LE, Grant BD.Delayed hypersensitivity (DH) responses of normal and immunodeficient horses were evaluated with antigens [dinitrochlorobenzene (DNCB), keyhole limpet hemocyanin (KLH)] and phytolectins [phytohemagglutinin (PHA), concanavalin A (Con A)]. Immunologically normal horses sensitized with 5 daily applications of 2 mg of DNCB developed positive skin reactions upon challenge with 0.4 mg of DNCB. The delayed onset of the reaction and the predominately mononuclear cell infiltration at the test site indicated these were DH reactions. Normal horses sensitized with 500 microgram of KLH and challenged with ...
Smith HJ.A group of seven ponies naturally infected with large numbers of small strongyles and raised under conditions to minimize reinfection were treated periodically over a three year span with thiabendazole at the rate of 44 mg/kg body weight. Based on the absence of worm eggs in the feces following each treatment, thiabendazole removed the adult strongyles present with a new population subsequently developing by maturation of inhibited larvae. It took as many as four or five treatments to eliminate or reduce significantly the worm burdens present in the ponies under the conditions of this study. S...
Madison JB, Ziemer EL.Purified streptococcal M protein was injected into one intercarpal joint in three horses hyperimmunised with Streptococcus equi M protein vaccine. The contralateral joints were injected with pH adjusted polyionic solution. All antigen-injected joints developed a severe suppurative synovitis (mean synovial fluid nucleated cell count = 102,200 x 10(6) cells litre-1). Eosinophils were found in the synovial fluid and in synovial membrane biopsy specimens of two of the horses. Immune complexes were not demonstrated in the synovial membrane. Two horses are described that developed synovial fluid eos...
Jensen-Jarolim E, Einhorn L, Herrmann I, Thalhammer JG, Panakova L.Both humans and their most important domestic animals harbor IgE and a similar IgE receptor repertoire and expression pattern. The same cell types are also involved in the triggering or regulation of allergies, such as mast cells, eosinophils or T-regulatory cells. Translational clinical studies in domestic animals could therefore help cure animal allergies and at the same time gather knowledge relevant to human patients. Dogs, cats and horses may spontaneously and to different extents develop immediate type symptoms to pollen allergens. The skin, nasal and bronchial reactions, as well as chro...
Ozaydın T, Celik I, Sur E, Oznurlu Y, Uluısık D.We attempted to characterize the cytochemical staining patterns of leukocytes and to determine the percentages of alpha-naphthyl acetate esterase (ANAE) and acid phosphatase (ACPase) positive lymphocytes in peripheral blood of thoroughbred foals at different ages. Blood samples were obtained from the jugular veins of 60 healthy thoroughbred foals, 1 day, 3 days and 1 year old. Each age group included 10 male and 10 female animals. Peroxidase (PO) activity was detected in neutrophils, eosinophils and monocytes. Lymphocytes were negative for PO staining. Periodic acid-Schiff (PAS) staining was o...
Lindberg R, Nygren A, Persson SG.The histology from rectal biopsy specimens taken 1980-1990 on 131 occasions from 116 horses, age 1-18 years, with clinical signs of intestinal disease was evaluated and classified retrospectively. In 40 horses, autopsy results were studied for comparison. Biopsy specimens (21 horses) and post mortem rectal tissue (9 horses) from 30 healthy horses, age 4-22 years, were used as controls. In 105 clinical cases, a biopsy was performed on only one occasion, while repeat biopsy was performed in 11 cases. Specimens showed pathological changes in 60 horses. The findings were classified into acute, chr...
Winder NC, Gruenig G, Hermann M, Howald B, von Fellenberg R.Equine respiratory secretions (RS) collected before (33 horses) and after (76 horses) slaughter were evaluated cytologically and grouped according to the histological diagnosis of the lungs from which they were obtained. The histological categories included normal lungs (control; 17 horses), chronic small airway disease with mild (23 horses), moderate (13 horses) and severe lesions (25 horses), interstitial pneumonia (13 horses), pulmonary eosinophilic infiltration (13 horses) and pulmonary haemorrhage (5 horses). On a group basis there were significantly more neutrophils in RS of horses with ...
Kalsow CM, Dwyer AE, Smith AW, Nifong TP.There is no direct verification of pineal gland involvement in human uveitis. Specimens of pineal tissue are not available during active uveitis in human patients. Naturally occurring uveitis in horses gives us an opportunity to examine tissues during active ocular inflammation. We examined the pineal gland of a horse that was killed because it had become blind during an episode of uveitis. The clinical history and histopathology of the eyes were consistent with post-leptospiral equine recurrent uveitis. The pineal gland of this horse had significant inflammatory infiltration consisting mainly...
Cunningham FM, Andrews M, Landoni MF, Lees P.Calcium ionophore A23187 induced time and concentration dependent production of immunoreactive leukotriene (LT) B4 by equine heparinized whole blood in vitro. Time dependent production of immunoreactive LTB4 by equine neutrophils and immunoreactive LTC4 by equine eosinophils in vitro was also demonstrated. The 5-lipoxygenase activating protein (FLAP) inhibitors, BAY X 1005 and BAY Y 1015, produced concentration dependent inhibition of ionophore-induced LTB4 synthesis by equine whole blood (mean +/- SEM IC50s n = 5; 6.14 +/- 0.28 microM vs. 12.30 +/- 0.75 microM for BAY Y 1015 and BAY X 1005, r...
French RA, Meier WA, Zachary JF.Tissues from a 9-year-old American Standardbred gelding with a history of anorexia, mild colic, and unexpected death were submitted to the Laboratories of Veterinary Diagnostic Medicine at the University of Illinois for histopathologic examination. Microscopic diagnoses were severe subacute, diffuse eosinophilic colitis with intralesional protozoa and a subacute to chronic eosinophilic portal hepatitis with granuloma formation. Two tissue-invading, ciliated protozoa were identified in large numbers within the colonic mucosa. The ciliates were Polymorphella ampulla and Cycloposthium sp., Phylum...
Rhiner T, Fettelschoss V, Schoster A, Birkmann K, Fettelschoss-Gabriel A.Previously, virus-like particle (VLP)-based self-vaccinations targeting interleukin (IL)-5 or IL-31 have been suggested to treat equine insect bite hypersensitivity (IBH), a seasonal recurrent allergic dermatitis in horses. The IL-5-targeting equine vaccine significantly reduced blood eosinophil counts in horses, similar to human monoclonal antibodies targeting IL-5 or the IL-5 receptor alpha (IL-5Rα). Previous studies in humans have also reported an additional effect on reduction of basophil counts. The aim of the present study was to evaluate whether an equine anti-IL-5 vaccine affected blo...
The aim of our study was to analyze circadian rhythm of the hematological profile of horses housed in a loose box and paddock during the different seasons (spring, summer, autumn, and winter). Blood samples were performed every 4 h for 48 consecutive hours. Red blood cells (RBCs), hemoglobin (HGB), hematocrit (HCT), white blood cells (WBCs), platelets (PLTs), and leukocyte subpopulations (neutrophils, basophils, eosinophils, lymphocytes, and monocytes) were analyzed, and, at the same time, environmental conditions were recorded. A statistically significant effect of housing conditions ( < 0...
Oddsdóttir C, Jónsdóttir HK, Sturludóttir E.Few studies have been conducted on haematological reference intervals (RIs) in Icelandic horses. Reference intervals have been published for Icelandic horses in Austria and a preliminary study in Iceland compared haematological values in riding horses to published RIs for other breeds as well as Icelandic horses abroad. Haematological parameters can vary greatly due to factors such as breed, gender, age, reproductive status, and training, as well as feeding, prior exercise and management method. Icelandic broodmares are kept on pasture under supervision throughout the year, with haylage provid...
Vitale V, Bindi F, Briganti A, Bonelli F, Parietti C, Sgorbini M.Bronchoalveolar lavage fluid (BALF) cytology is used for the diagnosis of non-infectious lower airway inflammation in equids. Discrepancies have been reported in the differential cell count when different staining methods were used both in humans and horses. The objective of this study was to compare the results of BALF cytology in donkeys using four different staining methods: modified May-Grunwald Giemsa (mMGG), Diff-Quick (DQ), Toluidine blue (TB) and Perls Prussian blue (PPB). Nine healthy Amiata female donkeys were enrolled. The BAL procedure was performed as previously described and pair...
